Yellow fog inhibitor for photographic material



Patented Apr. 15, 1941 Fritz Dersch and Newton Heimbach, Binghamton,

N. Y., assignors, by mesne assignments, to General Aniline & Film Corporation, New Yor N. Y., a corporation of Delaware N 0 Drawing.

Our invention relates to photographic materials containing anti-yellow fogging agents, and more particularly to the use of sulfonium iodides and related compounds as such agents.

It is well known that many light sensitive Application May 4, 1939, Serial No. 271,720

.11 Claims.

emulsions, such as gelatine-silver halide emulsions, have a'tendency to fog. There are two general types of this fog: first, ordinary grey fog such as is caused by premature exposure, by

excessive ripening of the emulsion, or by ordinary aging of the emulsion; and, secondly, so-called yellow fog, color fog, or dichroic fog. This yellow fog is essentially a colloidal deposit of silver, of which the great degree of subdivision or minute particle size chiefly determines the color intensity and general appearance. The fog is usually predominantly yellow and is mostapparent in the lighter portions of a negative. The colloidal particles of silver may, however, appear green by reflected light and yellow or red by transmitted light, which effect is often referred to as color log or dichroic fog.

Yellow fog may be caused by the emulsion itself or one of its constituents, or by some factor in the preparation of the emulsion. It may also result from a variety of conditions in connection with the processing of the film. For example,-

the presence of traces of fixing solution or of excess silver halide solvent such as sulflte in the developing bath, or the use of nearly exhausted developing or fixing baths, will commonly cause yellow fog. lIhe problem is especially prevalent in the processing of X-ray films, where thick emulsions and the repeated use of partially ex hausted fixing solutions contribute to the production of yellow fog.

Other possible causes of yellow fog have been described in the literature pertaining to this art, and various remedies have been suggested. For example, United States Patent No. 2,059,642 suggests the use of a mixture of soluble gold and mercury salts to prevent both grey and yellow fog. Likewise, German Patent No. 635,605 (1936) and Photographische Korrespondenz, Band 72, Seite 148, disclose the use of diphenyliodonium salts in emulsions and in developing, washing or fixing baths as tendin g to prevent. yellow fog. Cas'sells Cyclopaedia of Photography, 1912, vol. 1, p. 266, also recommends treatment with a bath of sodium sulflte and potassium cyanide to reof sensitivity. Oneobject of our invention is. to provide a new class of fog inhibiting agents which tend to prevent the formation of yellow fog in photographic materials while avoiding the dimculties and defects of the'prior art procedures.

Another object is to provide anti-yellow fog agents which may be incorporated in a photographic emulsion or in a surface or substratum layer without noticeably decreasing the sensitivity of the emulsion.

A still further object is to provide new yellow fog inhibitors which may be incorporated in the developing bath itself or in a separate processing bath.

Still another object is the treatment of gela tines which normally cause yellow fog when used in photographic emulsions with compounds which decrease this yellow fogging tendency.

Further objects and advantages will appear from the following specification.

We have found that the above objects are accomplished by the use of sulfonium iodides and the related selenium and tellurium compounds as well as the addition products or salts of the above compounds with various metal and alkyl iodides, as yellow fog inhibitors.

These compounds all contain the grouping wherein Y is sulfur, selenium, or tellurium, and I represents iodine. While we do not wish to limit ourselves to any particular theory, it is our 'three other valences of the'Y atom" are supplied, so long as they are supplied by organic radicles. Thus our invention includes compounds of the general formulae:

and

iii- 4 Ra v wherein Y is sulfur, seleniumnor tellurium as above, and wherein the substituents R1, R2 and Rs may be substituted or unsubstituted alkyl,

' cycloalkyl, aryl aralkyl, or heterocyclic groups and may be like or unlike, and wherein V is a heterocyclic grouping.

Typical compounds having these desirable properties thus include: alkyl sulfonium selenonium-, and telluronium iodides such as trimethyl sulionium iodide, triethyl sulfonium iodide, and methyl diethyl sulfonium iodide; alkyl-cycloalkvl sulfonium-, selenoniumand telluronium iodides, such as dimethyl cyclohexyl sulfonium iodide; substituted aryl sulfonium-,

selenonium-, and telluronium iodides, for example, phenyl-bis-(p-bromophenyl)- sulfonium iodide alkyl-aryl sulfonium-, selenonium-, and telluronium iodides, for instance methyl diphenyl telluronium iodide r alkyl-aralkyl sulfonium-, selenonium-, and telluronium iodides, such as methyl dibenzyl sulfonium iodide heterocyclic jsulfonium-, selenoniumand 'tellu ronium iodides, for example methyl tetramethylene sulfonium iodide S I I CHr-CH: CH:

better understand the nature and scope of this invention, the following specific examples are given without anyintention of limiting the invention thereto.

Example 1 To 500 g. of a light sensitive gelatino-silver halide emulsion which normally shows yellow fog,

melted at C., are added from 10 to 20 mgjof trimethyl sulfonium iodide. The mixture is coated on a suitable support, chilled, and dried in the customary manner. The emulsion thus treated is free from yellow fog.

Example 2 The trimethyl sulfonium iodide of the preceding example may be applied to the emulsion by including it in a surface coating. In such a case the amount used should be so chosen that the same concentration of sulfonium iodide per unit area of coated film based on relative thickness of surface and emulsion coatings, is obtained as.

in Example 1. Thus, if the surface coating is one-tenth the thickness of the emulsion coating, approximately ten times as much trimethyl sulfonium iodide, or from 100 to 200 mg., is added to 500 g. of surface coating solution. The film 1 formation of such fog.

and phenyl thio-o-diphenylene sulfonium iodide and finally, addition products or salts of any of the above compounds with various metal and alkyl iodides, for instance with cadmium iodide, mercuric iodide, bismuth iodide, and iodoform. Typical examples of suchaddition products are:

[(cm) aSIJCdIa [(CaHs) :(CI-Is) SJJHgIz [(CzI-Is) 38.110111":

[(CzHs) 33.111311:

In order that those skilled in the-art may having a surface coating thus treated is free from yellow fog.

Example -3 To one liter of a common developer solution, such as any standard metol-hydroquinone formula, is added 20 to 30 mg. of triethyl sulfonium iodide. A film having an emulsion which normally exhibits a tendency to form yellow fog may be developed in this solution without the Example 4 To 500 g. of a light sensitive gelatino-silver halide emulsion as in Example 1, melted at 40 C.,

are added from 10 to 20 mg. 'of phenyl thio-odiphenylene sulfonium iodide. The mixture is coated on a suitable support, chilled and dried in the usual way. The emulsion thus treated is free from yellow fog.

Example 5 To 500 g. of a light sensitive gelatino-silver halide emulsion as in Example 1, melted at 40 C., are added from 10 to 20 mg. of triethyl selenonium iodide. The mixture is coated on a suitable support, chilled and dried in the usual way. The emulsion thus treated is free from yellow fog.

' Example 6 To 500 g. of a light sensitive gelatino-silver halide emulsion as in Example 1, melted at 40 C., are added from 10 to 20 mg. of triethyl sulfonium iodide. The mixture is coated on a suitable support, chilled and dried in the usual way. The

, emulsion thus treated is freefrom yellow fog.

We claim:

1. A photographic material containing as a yellow tog inhibitor for silver halide emulsions an organic compound having the grouping wherein Y is a tetravalent atom selected from the.

group consisting of sulfur, selenium, and tellurium and wherein the dangling valences are supplied by organic radicles.

g 2. A photographic material containing as a yellow fog inhibitor for silver halide emulsions an organic compound having the grouping and wherein the dangling valences are supplied by organic radicles.

3. A photographic material containing as a yellow log inhibitor for silver halide emulsions an organic substance corresponding to the formula wherein Y is a tetravalent atom selected from the group consisting of sulfur, selenium, and tellurium and wherein the dangling valances are supplied by organic radicles.

4. A photographic material containing as a yellow tog inhibitor for silver halide emulsions a substance corresponding to the formula wherein-Y is a tetravalent atom selected from the group consisting of sulfur, selenium, and

yellow tog inhibitor tor silver halide emulsions a substance corresponding to the formula ta s Ra wherein is a heterocyclid group, and R: is a member selected from the group consisting of substituted and unsubstituted alkyl, cycioalkyl, aryl, aralkyl, and heterocyclic groups.

6. A photographic material containing as a yellow tog inhibitor for silver halide emulsions a substance corresponding to the formula wherein Y is a tetravalent atom selected from I methyl suli'onium iodide as a yellow tog inhibitor for silver halide emulsions.

9. A light sensitive photographic gelatino-silve halide emulsion containing from 10 to 20 mg. of

trimethyi sulionium iodide per 500 g. or emulsion as a yellow flog inhibitor.

10, A photographic material containing tri-' ethyl snlionium iodide as a yeiiow fog inhibitor is a heterocyclic group and R3 is a member selected iron: the group consisting of substituted and unsubstituted alkyl, cycloaikyi, aryi, aralkyl.

and heterccyciic groups. V

5, A, photographic material containing as a for silver halide emulsions.-

li. A light sensitive photographic gelatinosilver halide emulsion containing from 10 to 20 mg otj methyl sultonium iodide'per"500 g. 01

emulsion. as a yellow fog inhibitor.

FRIIZ DERSCH. NEWTON CH 

